Physical unclonable functions (PUFs) offer a promising defensive measure against the escalating challenges posed by the increasingly rampant counterfeit products. Conventional PUF materials with a singular physical property encounter limitations in encoding flexibility and capacity. Here, we propose a dual-color center diamond-based PUF (D-PUF) ink that exploits four diverse optical characteristics of dual-color center in diamond to design a concealable multi-level cryptographic authentication protocol. Through simple writing, stamping, or spraying, intricate covert random patterns can be directly generated on the objects, which are imperceptible under visible light. When challenged by a 532 nm laser, the D-PUF exhibits four distinct optical responses, including Raman, zero phonon line (ZPL) of germanium vacancies (GeV), ZPL of silicon vacancies (SiV), and the intensity ratios of these ZPLs. These responses were harvested simultaneously to construct the four-level separate encodable matrices. Furthermore, M-ary encoding algorithms were implemented to encrypt PUFs with flexibility. The resulting multi-level PUF system attains notable uniqueness, repeatability, extensive encoding capacity (> 10⁴⁸¹⁶⁴/(100 pixels)²), and ultra-high information entropy (6 bits/pixel). This study inspires designing new generations of multi-level PUFs with enhanced coding flexibility and holds significant promise for applications in print security.

As a novel solution-processable laser material with excellent optical properties, high biocompatibility, and low toxicity, the intrinsic value of carbon dots and their role in optimizing small-scale lasers as a gain medium have received extensive attention. In this review, we systematically summarize a series of properties of carbon dots themselves and the carbon dot (CD) lasers fabricated based on them. Specifically, we first summarize the photoluminescence principle of carbon dots as well as their synthesis and modification methods. Secondly, we organize the current types of CD lasers. Finally, we summarize the applications of carbon dots and CD lasers, the current challenges they face, and provide outlooks and speculations for their future. It is hoped that this review can help other researchers comprehensively and completely understand or review the overall picture of carbon dots and CD lasers in the shortest possible time.

Energy transfer between chemiluminescence (CL) donor and acceptor enables the tunable long-wavelength emission for multidisciplinary applications. In this work, the carbon nanodots (CDs) with sp³-hybrid carbon nitride framework exhibit a conspicuous tunable CL wavelength in luminol–H₂O₂ reaction with ultrahigh energy transfer efficiency. The density functional theorical calculations and experimental surveys reveal that the synergistic effect of singlet/triplet mixed electron exchange between the CD and luminol–H₂O₂ reaction enable the efficient energy transfer, and the concentration-dependent distance between the luminol donor and CD acceptor mutate the efficiency of singlet/triplet electron exchange, leading to the efficient concentration-dependent CL emission. With the novel CL emission, an advanced paper-based CL system is established with the CDs and luminol–H₂O₂ reaction, and the applications of information encryption and anti-counterfeiting are achieved. This work paves a new paradigm to understand the energy transfer mechanism in CL process, and may inspire the design of new CL architecture.

Humidity sensors have attracted considerable attention for their capability for real-time, continuous monitoring of critical physiological information, thus offering valuable insights into human health. Two-dimensional hexagonal boron nitride (h-BN) has emerged as an attractive material for humidity sensing due to its high specific surface area and excellent chemical stability. However, the low hydrophilicity of h-BN limits its ability to adsorb water molecules, resulting in reduced sensitivity and slow response times. Herein, capacitive humidity sensors consisted of amine-functionalized h-BN nanosheets have been developed. The introduction of amine groups modulates the hydrophilicity of pristine h-BN by forming hydrogen bonds, promoting interactions with water molecules. The h-BN-based sensor shows significantly improved performance, including high sensitivity (124,136 pF/%RH), large response (5,268,192%), and rapid response and recovery time (2.39 s/1.77 s). These findings demonstrate that amine functionalization can effectively enhance both water adsorption capacity and sensor performance, providing a promising approach for highly sensitive and responsive humidity sensors.

The COVID-19 pandemic has underscored the significance of antibacterial protective materials. Utilizing high-performance antibacterial masks proves to be effective in preventing the spread of respiratory diseases. Herein, we demonstrate a self-cleaning antibacterial mask constructed from the fiber@ZnO composite membrane, utilizing the strong interfacial adhesion of polydopamine (PDA). With a ZnO NPs immersion solution concentration of 1.0 mg/mL, the ZnO NP content in fiber@ZnO reaches 6.5%. The fiber@ZnO demonstrates bactericidal rates exceeding 99% against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria, and exhibits an inhibition rate exceeding 99.99% against the H1N1 influenza virus. The hydrogen bonding and electrostatic interaction between ZnO nanoparticles (NPs) and PDA can keep a stable combination of NPs and fiber. Antibacterial masks constructed by the fiber@ZnO composite membrane exhibit superior self-cleaning performance and effectively eliminate pathogenic bacteria in aerosols compared with commercial N95 masks. The mussel-bionic strategy presents a viable approach for developing novel antibacterial fibers, with significant application potential in reducing the risk of human infection and preventing the re-transmission of pathogens.

As one promising carbon-based material, sp³-hybrid carbon nitride has been predicted with various novel physicochemical properties. However, the synthesis of sp³-hybrid carbon nitride is still limited by the nanaoscale, low crystallinity, complex source, and expensive instruments. Herein, we have presented a facile approach to the sp³-hybrid carbon nitride nano/micro-crystals with microwave-assisted confining growth and liquid exfoliation. Actually, the carbon nitride nano/micro-crystals can spontaneously emerge and grow in the microwave-assisted polymerization of citric acid and urea, and the liquid exfoliation can break the bulk disorder polymer to retrieve the highly crystalline carbon nitride nano/micro-crystals. The obtained carbon nitride nano/micro-crystals present superior blue light absorption strength and surprising photoluminescence quantum yields of 57.96% in ethanol and 18.05% in solid state. The experimental characterizations and density functional theory calculations reveal that the interface-trapped localized exciton may contribute to the excellent intrinsic light emission capability of carbon nitride nano/micro-crystals and the interparticle staggered stacking will prevent the aggregation-caused-quenching partially. Finally, the carbon nitride nano/micro-crystals are demonstrated to be potentially useful as the phosphor medium in light-emitting-diode for interrupting blue light-induced eye damage. This work paves new light on the synthesis strategy of sp³-hybrid carbon nitride materials and thus may push forward the development of multiple carbon nitride research.

Easy non-radiative decay property of long-lived triplet excitons in aqueous solution obstructs their applications in aquatic surroundings. Recently reported phosphorescence phenomena in aqueous solution have excited researchers enormously but achieving full-color water-soluble phosphorescent carbon nanodots (CNDs) is still a challenging issue. Herein, full-color phosphorescence of water-soluble CNDs has been demonstrated by triggering their triplet excitons through nanospace domain confinement, and Förster energy resonance transfer is used for further tuning phosphorescence range. The phosphorescence spans across most of the visible spectrum, ranging from 400 to 700 nm. In an aqueous solution, the CNDs exhibits blue, green, and red phosphorescence, lasting for approximately 6, 10, and 7 s, respectively. Correspondingly, the phosphorescence quantum yields are 11.85%, 8.6% and 3.56%, making them readily discernible to the naked eyes and laying a solid foundation for practical application. Furthermore, phosphorescence flexible optical display and bioimaging have been demonstrated by using the multicolor CNDs-based nanomaterials, showing distinct superiority for accuracy and complete display and imaging in complex emission background.

The emergence of novel self-powered humidity sensors has attracted considerable attention in the fields of smart electronic devices and personal healthcare. Herein, self-powered humidity sensors have been fabricated using a moisture-driven energy generation (MEG) device based on asymmetric tubular graphitic carbon nitride (g-CN) films prepared on anodized aluminum (AAO) template. At a relative humidity (RH) of 96%, the MEG device can provide an open-circuit voltage of 0.47 V and a short-circuit current of 3.51 μA, with a maximum output power of 0.08 μW. With inherent self-powered ability and humidity response via current variation, an extraordinary response of 1.78 × 10⁶% (41%–96% RH) can be gained from the MEG device. The possible power generation mechanism is that g-CN/AAO heterostructure can form ion gradient and diffusion under the action of moisture to convert chemical potential into electrical potential, evoking a connaturally sensitive response to humidity. Self-powered respiration monitoring device based on the sensor is designed to monitor human movement (sitting, warming up, and running) and sleep status (normal, snoring, and apnea), maintaining excellent stability during cumulative 12-h respiration monitoring. This self-powered humidity sensing technology has promising potential for extensive integration into smart electronic and round-the-clock health monitoring devices.

Recently, the chemiluminescence (CL) induced by carbon nanodots (CDs) has intrigued researchers’ extensive interests in various applications due to its special light emission principle. However, the difficulty of synthesizing chemiluminescent CDs with full-spectrum emission severely hinders the further regulation of the CL emission mechanism. Herein, the multi-color-emissive chemiluminescent CDs are rational designed and further synthesized by regulating the sp²-hybrid core and sp³-hybrid surface from the citrate-ammonia molecular in a single solvothermal reaction. More experimental characterizations and density functional theory calculations reveal that the higher temperature can promote the crosslinking polymerization/carbonization of carbon core and the higher protonation of solvent can determine the core size of final CDs, resulting in the variant CL emission from molecular-, crosslinking- and core-states. Thus, the CL emission of the CDs can be further synthesized by tuning the luminescence chromophores in the formation process via regulating the temperature and solvent, enabling the applications of the CL CDs in illumination and information encryption. This study paves a new technology to understand the luminescence of CDs and affords an industry translational potential over traditional chemiluminescent molecular.

The spread of diseases caused by bacterial adhesion and immobilization in public places constitutes a serious threat to public health. Prevention of bacteria spread by the construction of an antibacterial surface takes precedence over post-infection treatment. Herein, we demonstrate an effective antibacterial surface with strong wear resistance by constructing cationic engineered nanodiamonds (C-NDs). The C-NDs with positive surface potentials interact effectively with bacteria through electrostatic interactions, where the C-NDs act on the phospholipid bilayer and lead to bacterial membrane collapse and rupture through hydrogen bonding and residual surface oxygen-containing reactive groups. In this case, bactericidal rate of 99.99% and bacterial biofilm inhibition rate of more than 80% can be achieved with the C-NDs concentration of 1 mg/mL. In addition, the C-NDs show outstanding antibacterial stability, retaining over 87% of the antibacterial effect after stimulation by adverse environments of heat, acid, and external abrasion. Therefore, an antibacterial surface with high wear resistance obtained by integrating C-NDs with commercial plastics has been demonstrated. The antibacterial surface with a mass fraction of 1 wt.% C-NDs improved abrasion resistance by 3981 times, with 99% killing of adherent bacteria. This work provides an effective strategy for highly efficient antibacterial wear-resistant surface, showing great practical applications in public health environments.